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author | Andrew Waterman <andrew@sifive.com> | 2018-09-23 16:40:17 -0700 |
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committer | Andrew Waterman <andrew@sifive.com> | 2018-09-23 16:40:17 -0700 |
commit | 70345f6d4ca85bb1e9ad5dea775c454a6b2df4cd (patch) | |
tree | a3b3b9cfd4a58c734b58329eb2d5fe708447e567 | |
parent | 3318c9e5c2594a64b19dcb6a6e3e0adc66172874 (diff) | |
download | riscv-isa-manual-pmp.zip riscv-isa-manual-pmp.tar.gz riscv-isa-manual-pmp.tar.bz2 |
tmppmp
-rw-r--r-- | src/machine.tex | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/src/machine.tex b/src/machine.tex index 8ec2e61..9d29642 100644 --- a/src/machine.tex +++ b/src/machine.tex @@ -2897,12 +2897,13 @@ PMP entry 0's A field is set to TOR, zero is used for the lower bound, and so it matches any address $y < {\tt pmpaddr}_0$. Although the PMP mechanism supports regions as small as four bytes, platforms -may specify coarser PMP regions. In general, the PMP grain is -$2^{G+2}$ bytes and must be the same across all PMP regions. When $G>0$, the -NA4 mode may not be selected. Furthermore, bits ${\tt pmpaddr}_i$[G-1:0] all -read as equal to ${\tt pmpcfg}_i$.A[1], i.e., all ones when the mode is NAPOT, -or all zeros when the mode is TOR or OFF. Bits ${\tt pmpaddr}_i$[G-1:0] do -not affect the address-matching logic. +may specify coarser PMP regions. In general, the PMP grain is $2^{G+2}$ bytes +and must be the same across all PMP regions. When $G>0$, the NA4 mode may not +be selected, and bit ${\tt pmpaddr}_i$[G-1] is hardwired to 0. Furthermore, +if $G \geq 2$, then bits ${\tt pmpaddr}_i$[G-2:0] all read as equal to ${\tt +pmpcfg}_i$.A[1]---i.e., all ones when the mode is NAPOT, or all zeros when the +mode is TOR or OFF. When $G>0$, bits ${\tt pmpaddr}_i$[G-1:0] do not affect +the address-matching logic. \begin{commentary} Software may determine the PMP granularity by writing zero to {\tt pmp0cfg}, |